1. Field of the Invention
This invention relates to a method for processing sheet material such as bank notes.
2. Description of Related Art
A method for processing sheet material such as banknotes by detecting measuring data by means of at least one sensor; deriving measuring results from the detected measuring data, and deriving a sorting class for the sheet material from the measuring results, wherein the step of deriving the sorting class for the sheet material comprises the step of locating a sorting node in a sorting tree in which all of said measuring results are within predetermined ranges of values, herein after referred to as domains, and wherein the sorting tree has the following characteristics:
domain is fixed at least for one measuring result in each sorting node of the sorting tree, PA1 for a domain of a measuring result in a sorting node of the sorting tree which is not the uppermost sorting node of the sorting tree, a corresponding domain of this measuring result is present in the assigned, higher sorting node, and PA1 the domain of a measuring result in the sorting node is a subdomain or equal to the domain of the corresponding measuring result of the assigned, higher sorting node,
is known from DE-OS 27 60 166 for example. Using a singler the sheet material present in a stack is separated into single sheets and delivered to a transport path which transports the singled sheet material through the apparatus.
A plurality of sensor units are mounted along the transport path, each sensor unit detecting measuring data of certain features of the sheet material and combining them into a measuring result. The structure of the sensor units used here is shown in DE-PS 27 60 165. Each sensor unit has a transducer that detects certain features of the sheet material and converts them into an electric signal. This signal is transformed in a signal processing stage. The usually analog signal is generally converted into digital measuring data here. The measuring data are then transformed into yes-or-no information in an evaluation unit of the sensor unit. This information constitutes the measuring result of the sensor unit and is stored, assigned to the particular sheet material, in a main memory.
The main memory is used as a connection for data exchange between the units of the apparatus. It can be accessed by all units which write or read the data necessary for processing the sheet material. One data record is stored in the main memory for a plurality of sheets in each case.
From the measuring results of the sensor units stored in the main memory for each sheet material, evaluation information is first produced in a central evaluation unit. A decision table stored in the evaluation unit is used to determine the destinations for the particular sheet material from the evaluation information. The destinations can be for example stackers for stacking the sheet material or shredders for destroying the sheet material. The destinations for the corresponding sheet material are also stored in the main memory. With reference to the stored information on the destination the sheet material is guided accordingly by the transport unit and the actual deposit checked.
In the known system, the sensor units deliver only yes-or-no information as a measuring result. For sensor units whose measuring results are not restricted to yes-or-no information but equipped with a higher information content, such as the length or width of the sheet material in mm, a dimension figure for the soiling or the like, the production of a decision table for deriving a sorting class or destination for the sheet material is elaborate and relatively quickly becomes too intricate and therefore error-prone.